Unpleasant tastes in water intended for human consumption pose serious problems, some of which can have health implications. The major objective of this study is to provide a framework for the evaluation of the taste of drinking water. Drinking water contains solutes which were either added in the purification process or were present in the source water and not removed. Generally, any taste is ascribed to the solutes. However, water itself is not tasteless. Its taste can be relatively intense and unpleasant under certain adaptation conditions. For example, adaptation to NaCl makes water taste bitter-sour. Under normal conditions the tongue is adapted to saliva which contains NaCl; changes in saliva produced by exercise, disease, etc. my alter the taste of water dramatically. We propose to study the taste of drinking water by 1) evaluating the taste of water itself and 2) evaluating the tastes of representative solutes and 3) determining the interactions among these tastes. The results of these studies may suggest ways to make water more palatable. In particular, information about interactions among tastes can be used to predict how the removal or addition of a particular substance will improve the taste of drinking water.